﻿34 
  

  

  THE 
  BEAN 
  THKIPS. 
  

  

  In 
  these 
  experiments 
  the 
  larvae 
  were 
  observed 
  to 
  feed 
  for 
  a 
  period 
  

   of 
  9 
  to 
  10 
  days 
  and 
  then 
  to 
  leave 
  the 
  plant 
  to 
  pupate, 
  and 
  10 
  to 
  12 
  

   days 
  were 
  required 
  between 
  hatching 
  from 
  the 
  egg 
  and 
  changing 
  to 
  

   prepupae. 
  

  

  During 
  the 
  year 
  1910 
  a 
  number 
  of 
  larvse 
  that 
  hatched 
  on 
  July 
  28 
  

   were 
  observed 
  to 
  change 
  to 
  prepupa? 
  on 
  August 
  7, 
  the 
  total 
  length 
  

   of 
  the 
  larval 
  stage 
  being 
  10 
  days, 
  with 
  an 
  average 
  mean 
  temperature 
  

   of 
  72.1° 
  F. 
  

  

  The 
  length 
  of 
  this 
  stage 
  later 
  in 
  the 
  summer 
  and 
  in 
  early 
  fall 
  

   for 
  this 
  locality 
  unfortunately 
  Avas 
  not 
  observed, 
  but 
  was 
  probably 
  

   somewhat 
  shorter 
  for 
  August 
  and 
  September 
  and 
  considerably 
  

   longer 
  in 
  October 
  and 
  November. 
  

  

  THE 
  PREPUPA 
  AND 
  PUPA. 
  

  

  As 
  the 
  prepupa 
  and 
  pupa 
  are 
  two 
  distinct 
  stages, 
  although 
  closely 
  

   related, 
  the 
  length 
  of 
  each 
  was 
  separately 
  determined. 
  These 
  two 
  

   stages 
  during 
  the 
  spring 
  of 
  1911 
  required 
  from 
  3 
  to 
  6 
  days 
  for 
  the 
  

   prepupa 
  and 
  from 
  9 
  to 
  14 
  days 
  for 
  the 
  pupa, 
  or 
  a 
  total 
  of 
  from 
  14 
  

   to 
  19 
  days. 
  The 
  results 
  are 
  shown 
  in 
  Table 
  VIII, 
  with 
  the 
  average 
  

   mean 
  temperature 
  for 
  each 
  experiment. 
  

  

  Table 
  VIII. 
  — 
  Length 
  of 
  prepupa! 
  and 
  pupal 
  stages 
  of 
  the 
  bean 
  thrips 
  at 
  Comp- 
  

   ton, 
  Col., 
  during 
  March 
  to 
  May, 
  1911. 
  

  

  Exp 
  

   No. 
  

  

  Larvae 
  changed 
  to 
  pre- 
  

   pupse. 
  

  

  Date. 
  

  

  Num- 
  

   ber. 
  

  

  Prepupse 
  

  

  changed 
  to 
  

  

  to 
  pupae. 
  

  

  Date. 
  

  

  Num- 
  

   ber. 
  

  

  Adults 
  

   emerged. 
  

  

  Date. 
  

  

  Num- 
  

   ber. 
  

  

  Length 
  of 
  stage. 
  

  

  Pre- 
  

  

  pupal. 
  

  

  Pupal. 
  

  

  Total. 
  

  

  Average 
  

   mean 
  

  

  tempera- 
  

   ture. 
  

  

  Mar. 
  31... 
  

   Apr. 
  10... 
  

   Apr. 
  19... 
  

   Apr. 
  24... 
  

  

  Total 
  

  

  Apr. 
  3 
  

  

  Apr. 
  15 
  

  

  Apr. 
  25 
  

  

  Apr. 
  29 
  

  

  Apr. 
  17 
  

   Apr. 
  24 
  

   May 
  4 
  

  

  May 
  10 
  

  

  Days. 
  

  

  Days. 
  

   14 
  

  

  Days. 
  

   17 
  

   14 
  

   15 
  

  

  59.2 
  

   59.5 
  

   57.9 
  

   56.9 
  

  

  In 
  the 
  month 
  of 
  July 
  these 
  stages 
  required 
  from 
  1 
  to 
  4 
  days 
  for 
  the 
  

   prepupa, 
  and 
  from 
  4 
  to 
  7 
  days 
  for 
  the 
  pupa, 
  or 
  a 
  total 
  of 
  from 
  5 
  to 
  11 
  

   days. 
  The 
  number 
  that 
  required 
  less 
  than 
  7 
  days, 
  however, 
  was 
  very 
  

   small. 
  During 
  this 
  month 
  the 
  average 
  mean 
  temperature 
  was 
  09° 
  F. 
  

  

  Table 
  IX 
  shows 
  the 
  results 
  of 
  these 
  experiments 
  and 
  the 
  average 
  

   temperature 
  for 
  each. 
  

  

  